Higgs transitions of spin ice

Frustrated magnets such as spin ice exhibit Coulomb phases, where correlations have power-law forms at long distances. Applied perturbations can cause ordering transitions which cannot be described by the usual Landau paradigm, and are instead naturally viewed as Higgs transitions of an emergent gauge theory. Starting from a classical statistical model of spin ice, it is shown that a variety of possible phases and transitions can be described by this approach. Certain cases are identified where continuous transitions are argued to be likely; the predicted critical behavior may be tested in experiments or numerical simulations.Comment: 23 pages, 10 figures; v2: published version with minor changes; ancillary file "Figures3D.nb" is a Mathematica (v7) notebook containing figures as rotatable 3D graphics (see http://www.wolfram.com/cdf-player/ for a free viewer

Real-time video correlator

Device provides two-dimensional correlation of video data. Operation is reliable, accurate, and predictable

History, College of Medicine: 1959-1968. Chapter 16: Department of Physiological Chemistry

Prepared for the Centennial of The Ohio State University

A gravity survey on the southern and central parts of the Isle of man

The Bouguer anomalies on the Isle of Man have been calculated from a network of 365 stations. The results ofrock density measurements made in the laboratory are stated. The main features shown by the gravity survey of the southern and central parts of the island are two elongated negative anomalies, centered at Foxdale and Dhoon. They are shown to be shallow in origin and it is suggested that they are due to the prensence of two large granite bodies lower in density than the surrounding Manx Slates and only represented at the surface by small outcrops. These two granites are apparently steep sided and lie on a north-east to south-west 'axis' but are not connected. The negative anomaly seen in part in the extreme South-west of the island is probably due to arise on the Poxdale granite. The elongated shape of the granites revealed by the survey can be correlated with the zones of metamorphism, the distribution of the mineral veins and the "anticline of cleavage". Comparing the mass of land above sea level with the mass deficiency due to the granites the southern and central parts of the Isle of Man are found to be under-compensated. A residual gravity map of the Peel area was prepared and it revealed a negative anomaly which is probably due to the baain of lower density Peel Sandstones. The louguer anomalies are found generally to be high on the Isle of Man. This emphasises the fact that the Irish Sea seems to be an area of large positive anomalies for gradients have also been observed on the mainland. No definite conclusion has been reached as to the cause of this Irish Sea anomaly or, indeed, that it has only one cause

An Empirical Study of Factors Associated with Physical Fitness of Sixth Grade Students

The purpose of this study is to determine if there was a relationship between the scores achieved on the Elementary School Fitness Test and the following factors: (1) the economic level of the neighborhood in which the schools were located; (2) family size; (3) achievement scores on the Iowa Basic Skills Test; (4) absenteeism of the students; and (5) health history of students

Optimal Image Reconstruction in Radio Interferometry

We introduce a method for analyzing radio interferometry data which produces maps which are optimal in the Bayesian sense of maximum posterior probability density, given certain prior assumptions. It is similar to maximum entropy techniques, but with an exact accounting of the multiplicity instead of the usual approximation involving Stirling's formula. It also incorporates an Occam factor, automatically limiting the effective amount of detail in the map to that justified by the data. We use Gibbs sampling to determine, to any desired degree of accuracy, the multi-dimensional posterior density distribution. From this we can construct a mean posterior map and other measures of the posterior density, including confidence limits on any well-defined function of the posterior map.Comment: 41 pages, 11 figures. High resolution figures 8 and 9 available at http://www.astro.uiuc.edu/~bwandelt/SuttonWandelt200

High Dynamic-Range Radio-Interferometric Images at 327 MHz

Radio astronomical imaging using aperture synthesis telescopes requires deconvolution of the point spread function as well as calibration of the instrumental characteristics (primary beam) and foreground (ionospheric/atmospheric) effects. These effects vary in time and also across the field of view, resulting in directionally-dependent (DD), time-varying gains. The primary beam will deviate from the theoretical estimate in real cases at levels that will limit the dynamic range of images if left uncorrected. Ionospheric electron density variations cause time and position variable refraction of sources. At low frequencies and sufficiently high dynamic range this will also defocus the images producing error patterns that vary with position and also with frequency due to the chromatic aberration of synthesis telescopes. Superposition of such residual sidelobes can lead to spurious spectral signals. Field-based ionospheric calibration as well as "peeling" calibration of strong sources leads to images with higher dynamic range and lower spurious signals but will be limited by sensitivity on the necessary short-time scales. The results are improved images although some artifacts remain.Comment: to appear in Comptes Rendus Physique (2011

Hidden unity in the quantum description of matter

We introduce an algebraic framework for interacting quantum systems that enables studying complex phenomena, characterized by the coexistence and competition of various broken symmetry states of matter. The approach unveils the hidden unity behind seemingly unrelated physical phenomena, thus establishing exact connections between them. This leads to the fundamental concept of {\it universality} of physical phenomena, a general concept not restricted to the domain of critical behavior. Key to our framework is the concept of {\it languages} and the construction of {\it dictionaries} relating them.Comment: 10 pages 2 psfigures. Appeared in Recent Progress in Many-Body Theorie

Tensor network states and algorithms in the presence of a global SU(2) symmetry

The benefits of exploiting the presence of symmetries in tensor network algorithms have been extensively demonstrated in the context of matrix product states (MPSs). These include the ability to select a specific symmetry sector (e.g. with a given particle number or spin), to ensure the exact preservation of total charge, and to significantly reduce computational costs. Compared to the case of a generic tensor network, the practical implementation of symmetries in the MPS is simplified by the fact that tensors only have three indices (they are trivalent, just as the Clebsch-Gordan coefficients of the symmetry group) and are organized as a one-dimensional array of tensors, without closed loops. Instead, a more complex tensor network, one where tensors have a larger number of indices and/or a more elaborate network structure, requires a more general treatment. In two recent papers, namely (i) [Phys. Rev. A 82, 050301 (2010)] and (ii) [Phys. Rev. B 83, 115125 (2011)], we described how to incorporate a global internal symmetry into a generic tensor network algorithm based on decomposing and manipulating tensors that are invariant under the symmetry. In (i) we considered a generic symmetry group G that is compact, completely reducible and multiplicity free, acting as a global internal symmetry. Then in (ii) we described the practical implementation of Abelian group symmetries. In this paper we describe the implementation of non-Abelian group symmetries in great detail and for concreteness consider an SU(2) symmetry. Our formalism can be readily extended to more exotic symmetries associated with conservation of total fermionic or anyonic charge. As a practical demonstration, we describe the SU(2)-invariant version of the multi-scale entanglement renormalization ansatz and apply it to study the low energy spectrum of a quantum spin chain with a global SU(2) symmetry.Comment: 32 pages, 37 figure

Explicit Construction of the Massive Supersymmetry Multiplets on Spacetime

A systematic method of constructing supersymmetry multiples of second quantized fields is given for the massive case and for any spin, starting from the irreducible representations of the Poincaré Lie superalgebra. This allows a full understanding of the nature of the auxiliary fields